The oxazolidinone antibacterial agents are a novel synthetic class of antimicrobials with potent activity against a number of human and veterinary pathogens, including gram-positive aerobic bacteria such as multiply-resistant staphylococci and streptococci, anaerobic organisms such as bacteroides and clostridia species & acid-fast organisms such as mycobacterium tuberculosis & mycobacterium avium.
Among lower antibacterial agents, Linezolid is a recent synthetic class of antimicrobial active against a number of pathogenic microorganisms. Linezolid [(S)—N-[[3-[3-fluoro-4-(4-morpholinyl)phenyl]-2-oxo-5-oxazolidinyl]methyl]acetamide] is disclosed in U.S. Pat. No. 5,688,792. It is marketed in US by Pfizer Inc having the brand name Zyvox®.
We have discovered and developed a novel intermediate and novel process, which is useful to prepare Linezolid. The process has the potential to lower the cost of commercial production of Linezolid. We also discovered novel key intermediates, which are more useful in the currently known process.
It has been found that U.S. Pat. No. 5,688,792 described the process for the preparation of Linezolid as described in scheme.

Further is U.S. 2007/0032472 A1 discloses two processes for the preparation of Linezolid in a different route as described in the following scheme.

The above mentioned base patent describes the preparation of hydroxy derivative by using hazardous chemical like n-BuLi at the temperature of −78° C. with reported very low yield. This process is not commercially viable and very difficult to handle BuLi as well as the very lower temperature.
In other mentioned patent process other unwanted isomer as well as unspecified impurities forms more, which are very difficult to remove and these impurities are continue to be present in the final drug Linezolid, and during the removal process yield becomes very low.
This has prompted and necessitated further research in an attempt to develop a novel route to avoid the formation of the impurity and to maximize the yield. We have discovered and developed a novel process for the preparation of novel intermediates, which are useful for the preparation of antimicrobial Linezolid. Another objective of the present invention is to provide improved method for the preparation of Linezolid avoiding the drawbacks of the hitherto known process. This process has the potential to significantly lower the cost of commercial production of Linezolid.